My PC is freezing

hello everyone.
i bought a new PC 6 months ago, and this is the configuration:
I7 2600 3.4ghz
GTX550 Ti
8 Gb DDR3 RAM
1.5 TB hard dive
Motherboard H67M series
So at first i thought it wasnt a big deal when my computer freezes, but i've noticed that its freezing more often now
At first it was realy rare, but now it is doing it almost every day,
so it doesnt matter what i do on my PC, my screen just becomes crazy, there are lots of red dots and fields on my screen and first 5 seconds my mouse moves and than it stops too. Once i was playing a some old games and listening to music in the background and it froze but the music keept going. But today i played a game and it froze again but my sound froze too!
Every time it freezes i need to restart my PC and it is annoying because sometimes when i do something important it freezes and i need to restart my PC! I also noticed that once it was like it frooze for 2 seconds and showed that red dots and fields but it returned to normal.
please help
ps sorry for my bad english